Cobalt metal precursors

ABSTRACT

A metal precursor and a method comprising decomposing a metal precursor on an integrated circuit device; and forming a metal from the metal precursor, wherein the metal precursor is selected from the group consisting of (i) a Co 2 (CO) 6 (R 1 C≡CR 2 ), wherein R 1  and R 2  are individually selected from a straight or branched monovalent hydrocarbon group have one to six carbon atoms that may be interrupted and substituted; (ii) a mononuclear cobalt carbonyl nitrosyl; (iii) a cobalt carbonyl bonded to one of a boron, indium, germanium and tin moiety; (iv) a cobalt carbonyl bonded to a mononuclear or binuclear allyl; and (v) a cobalt (II) complex comprising nitrogen-based supporting ligands.

FIELD

Metallization in integrated circuit devices.

BACKGROUND

Generally, limited atomic layer deposition (ALD)/chemical vapordeposition (CVD) precursor options currently exist for delivering highpurity cobalt films. These options tend to be even more limited whenrequirements such as source stability, high deposition rate for thermalonly ALD/CVD and liquid physical state at source temperature areconsidered. One commercially available precursor,μ2-η2-tertbutylacetylenedicobalthexacarbonyl (CCTBA) suffers from lowthermal stability. Low thermal stability leads to decomposition to anintractable solid in a source ampoule under delivery conditions whichnegatively impacts precursor dose as well as a functionality of a sourceliquid level sensor both of which are undesirable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section of a portion of a semiconductor substrateincluding a device side and formed from the device side to an oppositeside of the substrate.

FIG. 2 shows the structure of FIG. 1 following the introduction of adielectric layer on the sidewalls of the vias.

FIG. 3 shows the structure of FIG. 2 following the introduction of abarrier layer or the dielectric layer.

FIG. 4 shows the structure of FIG. 3 following the introduction of aconductive material in the vias and the formation of through-siliconvias (TSVs).

FIG. 5 illustrates computing device in accordance with oneimplementation of the invention.

DETAILED DESCRIPTION

Methods for introducing transition metals on integrated circuitsubstrate used are described. In one embodiment, methods for introducinga cobalt metal by way of a cobalt precursor are described.

In one embodiment, a method includes decomposing a transition metalprecursor (e.g., a cobalt metal precursor) on integrated circuit deviceand forming a metal from the metal precursor. In one embodiment, themetal precursor is selected from:

(i) a Co₂(CO)₆(R¹C≡CR²), wherein R¹ and R² are each individuallyselected from a straight or branched monovalent hydrocarbon group haveone to six carbon atoms that may be interrupted and substituted;

(ii) a mononuclear cobalt carbonyl nitrosyl;

(iii) a cobalt carbonyl bonded to one of a boron, indium, germanium andtin moiety;

(iv) a cobalt carbonyl bonded to a mononuclear or binuclear allyl; and

(v) a cobalt (II) complex comprising nitrogen-based supporting ligands.

In an embodiment where the metal precursor is Co₂(CO)₆(R¹C≡CR²), aninternal alkyne, tert-butylacetylene bridging a dicobalt-hexacarbonylcore is described. An internal alkyne is defined as an alkyne with R¹and R² substituents defining the acetylene (R¹C≡CR²) as opposed to aterminal alkyne which includes one substituent and a hydrogen (e.g.,R¹C≡CH). CCTBA is an example of a terminal alkyne, tert-butylacetylenebridging a dicobalt-hexacarbonyl core.

In an embodiment where the metal precursor is Co₂(CO)₆(R¹C≡CR²), R¹ andR² are individually selected from a straight or branched hydrocarbongroup having one to six carbon atoms which may be interrupted and/orsubstituted. Monovalent hydrocarbons, in one embodiment, include astraight or branched chain alkyl. Such straight or branched chain alkylhas one to six carbon atoms, in one embodiment, and one to four carbonatoms in another embodiment. An interruption is an interruption in achain of carbon atoms. In one embodiment, a straight or branched chaincarbon atoms may be interrupted by oxygen atom, a sulfur atom or anitrogen atom. In addition to embodiments allowing for interruptions ofa hydrocarbon group, in another embodiment, substituents of thehydrocarbon group (e.g., carbon atoms) may be substituted with, forexample, halide groups (e.g., CF₃). A representative hydrocarbon groupthat is both interrupted and substituted is, for example, an ester. Inone embodiment, the monovalent hydrocarbon group may be saturated (e.g.,an alkyl) or unsaturated (e.g., the group may contain one or more doublebonds).

Examples of representative precursors having the general formulaCo₂(CO)₆(R¹C≡CR²) where R¹ and R² each individually selected from alkylgroups having four or less carbon atoms are the following:

In another embodiment, a suitable cobalt precursor for forming a metalfrom the precursor on an integrated circuit substrate is a mononuclearcobalt carbonyl nitrosyl. Examples of mononuclear cobalt carbonylnitrosyl include, but are not limited to:

wherein R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶ and R¹⁷ areindependently selected from a straight or branched chain alkyl havingone to four carbon atoms.

In another embodiment, suitable cobalt precursors for forming a metalfrom the precursor on integrated circuit substrate include a cobaltcarbonyl bonded to one of a boron, indium, germanium and tin moiety.Representative cobalt precursors include, but are not limited to:

wherein R¹⁸, R¹⁹, R²⁰, R²¹, R²² and R²³ are independently selected froma straight or branched chain alkyl having one to four carbon atoms andR²⁰ and R²¹ may further individually be a substituted amine.

In another embodiment, a suitable cobalt precursor for forming a metalfrom the precursor on an integrated circuit substrate is a cobaltcarbonyl bonded to a mononuclear or binuclear allyl. Representativeexamples include, but are not limited to:

wherein R²⁴, R²⁵ and R²⁶ are independently selected from a straight orbranched chain alkyl having one to the three carbon atoms and L⁵, L⁶ andL⁷ are independently selected from one of:

In a further embodiment, suitable metal precursors for forming a metalprecursor on an integrated circuit include a cobalt (II) complexcomprising nitrogen-based supporting ligands. Representative examplesinclude:

wherein R³, R⁴, R⁵ and R⁶ are individually selected from a straight orbranched monovalent hydrocarbon group have one to three carbon atomsthat may be substituted and L¹, L², L³ and L⁴ are independently selectedfrom a substituted amine and quinuclidine.

A transition metal precursor such as a cobalt metal precursor describedabove may be used to form a metal, such as a cobalt metal on anintegrated circuit. One embodiment for forming a cobalt metal from oneof the noted precursor utilizes a coreactant introduced simultaneouslywith or subsequent to the introduction of the precursor to decompose theprecursor to cobalt metal. Suitable coreactants include, but are notlimited to, a hydrogen gas or hydrogen plasma; an ammonia gas or ammoniaplasma; a hydrozine such as N₂H₄, methylhydrazine ortertiarybutylhydrazine; a borane such as diborane or an organoborane; analane; or a silane such as monosilane, disilane or higher order silane.In one embodiment, a semiconductor substrate (e.g., integrated circuitsubstrate) is placed in a chamber suitable for CVD or ALD processing andthe precursor and a coreactant are introduced.

Cobalt is a metal that has been utilized in multilevel metallizationprocesses especially for PMOS work function layers of metal oxidesemiconductor field effect transistors (MOSFETs). Cobalt metal has alsobeen used as a barrier material for an interconnect line such as abarrier for a copper interconnect (to inhibit migration of copper intoan adjacent dielectric material). Cobalt metal can also be used asinterconnect material.

One application of the use of cobalt in the course of an integratedcircuit process is a process for metallization of through-silicon vias(TSVs). TSVs are utilized to produce three-dimensional integratedcircuit chip arrangements and allow for die-to-die stacking such as, forexample, stacking of dynamic random access memory (DRAM) on amicroprocessor die (e.g., wide I/O memory configuration).

FIGS. 1-4 illustrate a process for forming TSVs. FIG. 1 shows across-sectional side view of a portion of an integrated circuitsubstrate, such as a portion of a silicon chip at, for example, thewafer stage. Substrate 100 of portion of a chip includes device side 110representatively having a number of devices formed therein and thereonand back side 120 opposite device side 110. Disposed within substrate100 or through substrate 100 are TSVs 130 which extend from device side110 to back side 120. TSVs 130 may be formed by an etching process.

FIG. 2 shows the structure of FIG. 1 following the introduction of adielectric material into vias 130. FIG. 2 shows dielectric material 140of, for example, a silicon dioxide or insulating polymer introduced(deposited) along the sidewalls of vias 130.

FIG. 3 shows the structure of FIG. 2 following the introduction of abarrier layer in the vias. Referring to FIG. 3, FIG. 3 shows barrierlayer 150 disposed along the sidewalls of via 130 on dielectric layer140. In one embodiment, barrier layer 150 is a transition metal,particularly cobalt. A transition metal of cobalt may be deposited byALD or CVD techniques utilizing a cobalt metal precursor such asdescribed above. In a chamber suitable for ALD or CVD process, a metalprecursor is introduced into via 130 and decomposes in via to a cobaltmetal. One way to confine the introduction of cobalt metal into the viasis by masking back side 120 of the substrate. One way to foster thedecomposition of the cobalt metal precursor is through the introductionof a hydrogen gas, representatively introduced with the precursor. FIG.3 shows the structure following the decomposition of the precursor andthe formation of barrier layer (cobalt metal layer) 150 in vias 130.

FIG. 4 shows the structure of FIG. 3 following the introduction of aconductive material such as copper in the vias. FIG. 4 shows conductivematerial 160 of, for example, electrodeposited copper disposed in andfilling the vias.

It is appreciated that the above example is one example of depositingand use for a cobalt metal. The precursors described herein may be usedin such a process for such use or any other process or use involvingcircuits or semiconductor substrates.

FIG. 5 illustrates a computing device 200 in accordance with oneimplementation. Computing device 200 houses board 202. Board 202 mayinclude a number of components, including but not limited to processor204 and at least one communication chip 206. Processor 204 is physicallyand electrically connected to board 202. In some implementations atleast one communication chip 206 is also physically and electricallyconnected to board 202. In further implementations, communication chip206 is part of processor 204.

Depending on its applications, computing device 200 may include othercomponents that may or may not be physically and electrically connectedto board 202. These other components include, but are not limited to,volatile memory (e.g., DRAM), non-volatile memory (e.g., ROM), flashmemory, a graphics processor, a digital signal processor, a cryptoprocessor, a chipset, an antenna, a display, a touchscreen display, atouchscreen controller, a battery, an audio codec, a video codec, apower amplifier, a global positioning system (GPS) device, a compass, anaccelerometer, a gyroscope, a speaker, a camera, and a mass storagedevice (such as hard disk drive, compact disk (CD), digital versatiledisk (DVD), and so forth). Representatively, processor 204 is a systemon chip and is packaged in a microprocessor package assembly such asdescribed above with a DRAM die connected to a backside of processor 204in a wide I/O configuration and another memory device (e.g., a DRAMdevice) also connected to the package.

Communication chip 206 enables wireless communications for the transferof data to and from computing device 200. The term “wireless” and itsderivatives may be used to describe circuits, devices, systems, methods,techniques, communications channels, etc., that may communicate datathrough the use of modulated electromagnetic radiation through anon-solid medium. The term does not imply that the associated devices donot contain any wires, although in some embodiments they might not.Communication chip 206 may implement any of a number of wirelessstandards or protocols, including but not limited to Wi-Fi (IEEE 802.11family), WiMAX (IEEE 802.16 family), IEEE 802.20, long term evolution(LTE), Ev-DO, HSPA+, HSDPA+, HSUPA+, EDGE, GSM, GPRS, CDMA, TDMA, DECT,Bluetooth, derivatives thereof, as well as any other wireless protocolsthat are designated as 3G, 4G, 5G, and beyond. Computing device 200 mayinclude a plurality of communication chips 206. For instance, a firstcommunication chip 206 may be dedicated to shorter range wirelesscommunications such as Wi-Fi and Bluetooth and a second communicationchip 206 may be dedicated to longer range wireless communications suchas GPS, EDGE, GPRS, CDMA, WiMAX, LTE, Ev-DO, and others.

Communication chip 206 also includes an integrated circuit die packagedwithin communication chip 206 such as described above. The die mayinclude a cobalt metal introduced by way of one of the above-notedprecursors and used, for example, as a silicide for a transistor, aninterconnect or a barrier layer for an interconnect or TSV.

In further implementations, another component housed within computingdevice 200 may contain a microelectronic package including an integratedcircuit die such as described above.

In various implementations, computing device 200 may be a laptop, anetbook, a notebook, an ultrabook, a smartphone, a tablet, a personaldigital assistant (PDA), an ultra mobile PC, a mobile phone, a desktopcomputer, a server, a printer, a scanner, a monitor, a set-top box, anentertainment control unit, a digital camera, a portable music player,or a digital video recorder. In further implementations, computingdevice 200 may be any other electronic device that processes data.

In the description above, for the purposes of explanation, numerousspecific details have been set forth in order to provide a thoroughunderstanding of the embodiments. It will be apparent however, to oneskilled in the art, that one or more other embodiments may be practicedwithout some of these specific details. The particular embodimentsdescribed are not provided to limit the invention but to illustrate it.The scope of the invention is not to be determined by the specificexamples provided above but only by the claims below. In otherinstances, well-known structures, devices, and operations have beenshown in block diagram form or without detail in order to avoidobscuring the understanding of the description. Where consideredappropriate, reference numerals or terminal portions of referencenumerals have been repeated among the figures to indicate correspondingor analogous elements, which may optionally have similarcharacteristics.

It should also be appreciated that reference throughout thisspecification to “one embodiment”, “an embodiment”, “one or moreembodiments”, or “different embodiments”, for example, means that aparticular feature may be included in the practice of the invention.Similarly, it should be appreciated that in the description variousfeatures are sometimes grouped together in a single embodiment, figure,or description thereof for the purpose of streamlining the disclosureand aiding in the understanding of various inventive aspects. Thismethod of disclosure, however, is not to be interpreted as reflecting anintention that the invention requires more features than are expresslyrecited in each claim. Rather, as the following claims reflect,inventive aspects may lie in less than all features of a singledisclosed embodiment. Thus, the claims following the DetailedDescription are hereby expressly incorporated into this DetailedDescription, with each claim standing on its own as a separateembodiment of the invention.

1. A method comprising: decomposing a metal precursor on an integratedcircuit device; and forming a metal from the metal precursor, whereinthe metal precursor is selected from the group consisting of: (i) aCo₂(CO)₆(R¹C≡CR²), wherein R¹ and R² are individually selected from astraight or branched monovalent hydrocarbon group have one to six carbonatoms that may be interrupted and substituted; (ii) a mononuclear cobaltcarbonyl nitrosyl; (iii) a cobalt carbonyl bonded to one of a boron,indium, germanium and tin moiety; (iv) a cobalt carbonyl bonded to amononuclear or binuclear allyl; and (v) a cobalt (II) complex comprisingnitrogen-based supporting ligands selected from the group consisting of:

wherein R³, R⁴, R⁵ and R⁶ are individually selected from a straight orbranched monovalent hydrocarbon group have one to three carbon atomsthat may be substituted and L¹, L², L³ and L⁴ are independently selectedfrom a substituted amine and quinuclidine.
 2. The method of claim 1,wherein the transition metal precursor is a Co₂(CO)₆(R¹C≡CR²) and R¹ andR² are independently selected from a straight or branched chain alkylhaving one to the three carbon atoms.
 3. The method of claim 2, whereinthe transition metal precursor is selected from the group consisting of:


4. The method of claim 1, wherein the metal precursor comprises a amononuclear cobalt carbonyl nitrosyl selected from the group consistingof:

wherein R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶ and R′⁷ areindependently selected from a straight or branched chain alkyl havingone to four carbon atoms.
 5. The method of claim 1, wherein the metalprecursor is selected from the group consisting of:

wherein R¹⁸, R¹⁹, R²⁰, R²¹, R²² and R²³ are independently selected froma straight or branched chain alkyl having one to four carbon atoms andR²⁰ and R²¹ may further individually be a substituted amine.
 6. Themethod of claim 1, wherein the metal precursor is selected from thegroup consisting of:

wherein R²⁴, R²⁵ and R²⁶ are independently selected from a straight orbranched chain alkyl having one to the three carbon atoms and L⁵, L⁶ andL⁷ are independently selected from the group consisting of:


7. The method of claim 1, wherein forming the metal comprises combiningthe precursor with a coreactant.
 8. A method comprising: loading anintegrated circuit device in a deposition chamber; depositing atransition metal precursor on the integrated circuit device; anddecomposing the transition metal precursor with a coreactant; whereinthe transition metal precursor is selected from the group consisting of:(i) a Co₂(CO)₆(R¹C≡CR²), wherein R¹ and R² are individually selectedfrom a straight or branched monovalent hydrocarbon group have one to sixcarbon atoms; (ii) a mononuclear cobalt carbonyl nitrosyl; (iii) acobalt carbonyl bonded to one of a boron, indium, germanium and tinmoiety; (iv) a cobalt carbonyl bonded to a mononuclear or binuclearallyl; and (v) a cobalt (II) complex comprising nitrogen-basedsupporting ligands selected from the group consisting of:

wherein R³ is selected from a straight or branched monovalenthydrocarbon group have one to three carbon atoms and L is selected fromMe₂EtN, Me₃N, Et₃N and quinuclidine.
 9. The method of claim 8, whereinthe transition metal precursor is a Co₂(CO)₆(R¹C≡CR²) and R¹ and R² areindependently selected from a straight or branched chain alkyl havingone to the three carbon atoms.
 10. The method of claim 9, wherein thetransition metal precursor is selected from the group consisting of:


11. The method of claim 8, wherein the metal precursor comprises amononuclear cobalt carbonyl nitrosyl selected from the group consistingof:

wherein R⁴, R⁵, R⁶, R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴ and R¹⁵ areindependently selected from a straight or branched chain alkyl havingone to the three carbon atoms.
 12. The method of claim 8, wherein themetal precursor is selected from the group consisting of:

wherein R²² and R²³ are independently selected from a straight orbranched chain alkyl having one to the four carbon atoms and R²⁰ and R²¹may further individually be a substituted amine.
 13. The method of claim8, wherein the metal precursor is selected from the group consisting of:

wherein R²⁴, R²⁵ and R²⁶ are independently selected from a straight orbranched chain alkyl having one to the three carbon atoms and L², L³ andL⁴ are independently selected from the group consisting of:


14. The method of claim 8, wherein the coreactant is selected from thegroup consisting of a hydrogen gas or plasma, an ammonia gas or plasma,a hydrazine, a borane, an alane and a silane.
 15. A metal precursorselected from the group consisting of: (i) a Co₂(CO)₆(R¹C≡CR²), whereinR¹ and R² are individually selected from a straight or branchedmonovalent hydrocarbon group have one to six carbon atoms that may beinterrupted and substituted; (ii) a mononuclear cobalt carbonylnitrosyl; (iii) a cobalt carbonyl bonded to one of a boron, indium,germanium and tin moiety; (iv) a cobalt carbonyl bonded to a mononuclearor binuclear allyl; and (v) a cobalt (II) complex comprisingnitrogen-based supporting ligands selected from the group consisting of:

wherein R³, R⁴, R⁵ and R⁶ are individually selected from a straight orbranched monovalent hydrocarbon group have one to three carbon atomsthat may be substituted and L¹, L², L³ and L⁴ are independently selectedfrom a substituted amine and quinuclidine.
 16. The metal precursor ofclaim 15, wherein the transition metal precursor is a Co₂(CO)₆(R¹C≡CR²)and R¹ and R² are independently selected from a straight or branchedchain alkyl having one to the three carbon atoms.
 17. The metalprecursor of claim 16, wherein the transition metal precursor isselected from the group consisting of:


18. The metal precursor of claim 15, wherein the metal precursorcomprises a a mononuclear cobalt carbonyl nitrosyl selected from thegroup consisting of:

wherein R⁷, R⁸, R⁹, R¹⁰, R¹¹, R¹², R¹³, R¹⁴, R¹⁵, R¹⁶ and R¹⁷ areindependently selected from a straight or branched chain alkyl havingone to four carbon atoms.
 19. The metal precursor of claim 15, whereinthe metal precursor is selected from the group consisting of:

wherein R¹⁸, R¹⁹, R²⁰, R²¹, R²² and R²³ are independently selected froma straight or branched chain alkyl having one to four carbon atoms andR²⁰ and R²¹ may further individually be a substituted amine.
 20. Themetal precursor of claim 15, wherein the metal precursor is selectedfrom the group consisting of:

wherein R²⁴, R²⁵ and R²⁶ are independently selected from a straight orbranched chain alkyl having one to the three carbon atoms and L⁵, L⁶ andL⁷ are independently selected from the group consisting of: